IPA: /ˌʌnəˈsɛptɪd/
KK: /ʌnəˈsɛptɪd/
Not accepted or approved; not allowed or recognized.
Her proposal was unaccepted by the committee after much discussion.
Unaccepted → It is formed from "un-" (meaning not) and "accept" (from Latin "acceptare", meaning to receive or take). The word "unaccepted" means not received or not taken in.
Think of 'not' ('un-') receiving something ('accept') — that's why unaccepted means something that has not been received.